Imagine if your entire family was at the bedside of a loved one, but instead of listening to the doctor warning that the patient was in terminal decline, everyone preferred to quarrel over the wilting grapes instead.
Perhaps that is not the perfect analogy, but there is no doubt that the Earth’s vital signs – key measurements that reflect the state of life-sustaining functions – are flashing red and setting off every possible alarm.
The latest report from a consortium of 70 scientists contributing to the Indicators of Global Climate Change Initiative found that the Earth’s energy imbalance grew further in 2025, and its 10-year average reached a record high.
So what? If it’s just the surface temperature increase that we should be directly concerned with, why does this imbalance matter?
Unfortunately, the increase in surface temperature is already a cause for alarm. At 1.37 degrees higher than the historical average [a conservative assessment], global warming directly attributable to human activities is fast approaching the 1.5 degree “guardrail” advised by the Intergovernmental Panel on Climate Change (IPCC).
But a surface temperature increase is not the only measurement that we should be worried about, and it is just one of several key indicators of Earth system disruption.
The Earth energy imbalance is an estimate of the surplus heat that is stored in the oceans, ice, land and atmosphere due to global warming. It is a vital indicator of locked-in temperature increases that will be impossible to reverse on any meaningful timescale. And this imbalance is growing.
The report found the long-term average energy imbalance has risen significantly, moving from an average of 0.79W/m2 (watts per square metre) over the 2006–2018 period to 1.12W/m2 for the next period ending in 2025. This represents an approximately 40 per cent increase in the rate of heat accumulation in just over half a decade.
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The laws of physics require that this trapped energy must go somewhere – there is no magic technology that can suck it up or push it out into space. Thermal inertia guarantees that even if atmospheric greenhouse gas concentrations were stabilised tomorrow, global temperatures would continue to rise for decades as the ocean (which has absorbed more than 90 per cent of all the excess energy caused by the greenhouse effect) slowly releases this stored energy back into the broader climate system, making long-term warming effectively irreversible on human timescales.
The energy imbalance means that global temperatures could rise at even higher rates in the future, even if we start to reduce annual emissions. However, emissions – from burning fossil fuels, livestock and land use changes – are continuing to increase. Latest estimates measure them at 56.8GtCOe (gigatonnes) for 2025 and up to 60.6 GtCO2e when taking methane leaks into account – the highest on record.
Even though there are signs of structural change in the energy system, rising global energy demand continues to outpace deployment of renewables. Carbon dioxide – the main greenhouse gas – continues to accumulate rapidly in the atmosphere, further narrowing the remaining carbon budget required to stabilise global temperatures. Scientists now estimate that the carbon budget consistent with a 50 per cent chance of remaining below 1.5 degrees of warming will be exhausted in just three years.
Planet Earth is a big place; too big for our small brains to grasp what is unfolding in real time all around us. We react to immediate danger and proximate disasters and ignore slow-moving catastrophes. But the temperature anomalies, wind extremes, sea-level rise, off-the-chart rainfall events, marine heatwaves, floods and tidal surges are all happening as previous IPCC reports warned they would.
The EU’s Copernicus Earth monitoring and observation programme reported that the pronounced heatwave in northern Europe in May saw anomalies in which daily average temperatures reached more than 10 degrees above average in parts of France, England and Wales and more than 100 heat-related deaths in Spain. Copernicus scientists have concluded that this heatwave event is consistent with rapid warming. Recall that this corresponds to a global temperature increase of less than 1.4 degrees, but much more warming than that is in the pipeline.
What all of this means for Ireland depends on how all this ocean heat and resulting thermal expansion (water expands when heated) drives extreme weather and sea-level rise along our coast, and in the longer term, the extent to which the Amoc weakens. While there are still many uncertainties in this field of climate science, a further study, published in April in the journal Science Advances, estimated that the Amoc will weaken by around 50 per cent by the end of the century, a much more pessimistic scenario than was previously thought.
Sadhbh O’Neill is a climate and environmental researcher